The present invention generally relates to optical switches, and more particularly to optical switches having fibers with slanted ends and a method for making such optical switches.
Optical switches having a pair of optical fibers, each having a slanted surface, are known. These conventional switches operate by displacing at least one of the fibers to contact the other fiber (closed position) or to release contact with the other fiber (opened position). In the closed position, input light is transmitted from one optical fiber to the other with little or no transmission loss. In the opened position, input light is reflected at least partially from one of the fibers, leading to complete or partial transmission loss. Complete transmission loss occurs during total internal reflection, when light approaches a dielectric interface at or above a critical angle and is thereby inhibited from being transmitted to the other optical fiber. When the angle is below the critical angle, or the distance between the optical fibers is sufficiently small, some input light may cross the gap between the optical fibers and thereby frustrate the total internal reflection.
FIGS. 1-4 illustrate a conventional optical switch 10 which includes a pair of optical fibers 12 and at least one pair of chips 16. The chips 16 each have a slanted edge surface 18, and each of the optical fibers 12 has a slanted face 14. The slanted nature of the faces 14 of the optical fibers 12 allows for total internal reflection when a pair of faces 14 are separated from one another. As shown in FIGS. 1-2, the slanted faces 14 and the slanted edge surfaces 18 are coplanar, thereby allowing contact between each of the surfaces 18 and each of the faces 14 when the optical switch is in the closed position.
In the opened position (FIG. 1), input light 22 reaches the face 14, which acts as a dielectric interface, and is translated into reflected light 24 which is reflected in a direction transverse to the opposing face 14. In the closed position (FIG. 2), the input light passes through the faces 14 and continues its transmission from one optical fiber 12 to the other optical fiber 12.
Conventionally, the faces 14, 18 of, respectively, the optical fibers 12 and the chips 16 are formed by polishing. The polishing step is performed to create faces 14 which are coplanar to each other. One observed disadvantage is that during polishing, the optical fibers 12 become abraded at a different rate than the chips 16. Specifically, the optical fibers 12 abrade at a quicker rate than the chips 16. Thus, sometimes the polishing process can result in the faces 14 of the optical fibers 12 not being coplanar with the faces 18 of the chips 16, leading to a greater gap between the fiber end faces 14 than between the chips' edge surfaces 18 (FIG. 3). When the chips 16 contact each other (FIG. 4), a gap 25 remains between the faces 14 of the optical fibers 12. In such a circumstance, the input light 22 breaks up into a partially reflected portion 26 and a partially transmitted portion 28. The partially transmitted portion 28 indicates a higher than desired transmission loss.